Safety appliance for hoisting apparatus



Jan. 22, 1946.

J. E. DAVENPORT SAFETY APPLIANCE FOR HO ISTING APPARATUS File d Nov. 12, 1943 2 Sheets-:Sheet i INVENTOR.

w. m V A E S m A J 1946. .J. E. DAVENPORT SAFETY APPLIANCEAFOR HOISTING APPARATUS Filed Nov. .12, 1943 2 Sheets-Sheet 2' 0,. m V A 5 S W A J v B Patent ed Jan. 22, 1946 7. war

for nseion a' hoisting apparatus such as acrane hoistfand de igned to (automatically disconnect the power foropera'ting the 'hoist when the hoist boom is elevated to a critical position beyond which the boom' may strike the cab, ana thus heinventionrelatesto assesses arrange possibly injure theoperator and damagethecah and s hoist; mechanism. This type of' hoistin mechanism, utilizes a clutch which is operatively interposed between'the power unit "and the winding drum which controls therais'in g and lowerin'g of the boom about its pivotal axsyanagatmm clutch which is i'arranged to be released by ithe safety, device when the boom reaches the critical position aforesaid. The devices-heretofore designed 'for" effecting said release of the clutch,

e i p i a ly 'all instances emplo ed more I 1 APPARATUS n Q T: iIamesLE Richmond, Calif; assignor r .l 5,. Z. ofone-half to Leonard J; Quinn, 1

f *1 fl psn cisa' asta 12, 1943, Serial No 509,989

I 3. 1am c1;- 212-'-'-39) .t Figure 5 isa view similar to Figure 1, but showing a modified; construction and arrangement of the safety appliance. v l V The safety-appliance of my invention .is here illustrated in association with a hoisting apparae tus 6 including a base 1 'and a bearing block 8 in which the :lower end'of aboom 9 is pivotally mounted for'swinging upwardly or downwardly asmay be required. The boom may be moved-in a conventional-manner, such as by 11168118301 8. cable 12 attached to the :boom and operatively mounted on a suitable druml3 arrangedto'be connected through a clutch M to an appropriatepower unit (not shown). The clutch may be moved to amengaged or disengaged position, that is in position connecting or disconnecting the member of the clutch I-4 by means of a system l o the i ve t s to paves safety device o i characteri described: which may: be quickly and easily reset to operative positionfaft'er actuation. 7 Afurtherobject or re to provide a safety means of the character describdlwhich will'befrelatively simp e in s am: tion, canfbe manufactured at lowcost', and read; ilyapplied to different partsof thev'hoistappa- The; "nvention possesses other ob'jects an df fea tures of advantage, some of which, with thefore goin'gfwill be set forth in thefollowing 'd'escri'ption of the preferred forms of the invention which is" illustrated 'in'the drawings accompanying and forming'part'ofthe specification. *It' is to be uhdersto'od; however; that variations in the showing may be adopted within the scope of the invention as setforthinthe'claims. s 1 j 1 I Referringto saiddrawin'gsi Figure l isja side of a portion of a' crane hoist equipped with the safety appliance f'of my invention; parts being removed? and. shown in section in ,order to disclose theotherwise hidden portions. "The appliance is showniin set. position asjduring the normal positioning of tnepeom. v 1 Figure '2 is an enlarged longitudinal "sectional v e ta engthrough the safety appliance; as in dicated by the line 2-2 in Figure 1.,

[Figure 3-i's a fragmentary side view'lof the ap':

paratus showing a means of resetting .ithe safety appliance after it has been actuated, I Y

Figure 4- is aview corresponding to Figure 1 but showing the parts with the safety appliance in e tua edmsiti aq ture 'of the invention, is x of levers l8 connectedto the lower am It of'lever Hi. The power unit and the control mechanism including the lever 16 is usually enclosed in a suitable cab 20 supported on the base and formed large enough to. accommodate the operator, and as will be clear fromthe drawings, such mechanism and cabare positioned, to the immediate rear' of the bearing block 8 of the boom so that'there is no danger of the cab and mechanism or the operator being endangered unless the boom is elevated to'a vvertical position adjacent or against the cab. v l

' Briefly my'invention comprises a device mount-'- ed on but powered independentlyof the hoisting apparatus and operatively connectedto the clutch so as to move and hold the same in disengaged position, thedevice beingheld against interfer-' ing with the clutch during'the normal positioning' and operation of the boom, so that under its own power it will fiect instantaneous disengagement of the clutch as soon as the boom reaches thec'ritical position.

In the form of the invention'illustrated in Figures 1 to 4 inclusive, the means comprising an independently powered device for efiecting the movement of'the clutch and a latching mechanism for holding said device in operation during the normal functioning of the boom is in the:

form of aunit 2I mounted directly on the boom adjacent'but spaced appreciably from the pivotal I I means aforesaid I a a at Wiia1l M We fft i tle-HI of lever l6 and at the other end to a rod 24 extending, into thev housing. Within thehousing, the rod 24- is secured to a bar25 which. is connected to the far end 21 of the housing by one or more springs 28. The cable 23 is threaded over" a series of idler pulleys 29, 3|, and 32, the pulley.

29 being mounted on the base 1 whereas the. pulleys 3| and 32 are carried on an adjustable support 33 mounted on the boom. As will be understood, the cable is of such length that. under. the pull exerted by the springs, the lever 16 will.

be moved to the vertical position shown in Figure 4 so as to thus place the clutch in vertical or disengaged relation. In rder to permit the clutch M to bemoved to engaged as well as disengaged position without interference from the clutch releasing device, such as is. required for the normal operation of the hoisting apparatus, means are-provided for holding the bar; 26 in an advanced position against the resistance of the springs 28. "As here shown such means is in the form of a pair of latching dogs 34 which are fixedly held on a shaft 35 mounted in the housing 22. 31 to keep the dogs" 34 engaged with the bar however, as will be evident, by rotating theshaft 35 against the resistance of spring 31, the bar 28 will be released whereby under the pull of springs 28 the cable 12 will be drawn to place the clutch $7? in vertical position. Means are provided for causing the shaft 36 to be thus rotated to release the bar 26, when the boom is raised to apredetermined upright position, such means as here shown being in the simple form of a cable 38 which is connected to. a crank 39 on the shaft 36 and affixed such asby an eyebolt 4| to the base 1. As: will now be clear, when the boom is vraised highenough, such as indicated in Figure 4, the

cable 38. which is otherwise left in a slackened condition, becomes taut and causes the shaft 3.6- to rotate and release. the bar. In this manner the clutch will be. instantly disengaged and the further movement ofthe boom toward: the cab. willbe halted. Itmay be-explained in this connection. that most hoisting apparatus of the type to which. my invention is applied, have a means generally associated with the drum for checking the movement of the boom whenever the power unit is disconnected. It will thusvbe clear that when the clutch is placed in: neutral position,

movement of the. boom is stopped. Should it become necessary to immediately move the boom after the clutch is released, the clutch maybe replaced in engaged position by operating the'lever- [8 against the resistance of theisprings 28,

Preferably the eyebolt 4| is adjustably secured to the base so that the length oithe cable 28 may be varied and thus the point at which the safety device will be operated may be regulated. By appropriate adjustment of the pulley sup-- porting bracket 33, the cable 12 may be maintained in slackened condition without undue looseness during movement of the boom, and at the same time a straight pull may be assured between the rod 2d and cable and between the portions of the cable between the various pulleys and the lever. The bar 26 is preferably mounted. in guides 42 which assist in holding the bar in the extended position and during movement in the housing, and means are provided for retracting the bar against the resistance of the springs 28 so that the locking dogs may re-engage the bar and thus reset the device, after the latter has been tripped. A h'ere shown such means includes a. lever 43 The shaft is urged by means of a spring which may be either permanently or removably pivotedwto the boom such as indicated at 44. Pivoted to the lever is. hook 46 which may be attached to a pin 41 at the outer end of the rod .'24, and by swinging downward on the lever when th'e hook is engaged with the pin, the bar may .be'retracted until the dogs automatically catch the'bar. After the device has thus been reset,

.1 thelever, may be removed or placed in an unobtrusive position of the boom.

As previously stated, the safety device of my invention, may be positioned with little change in design, on portions of the hoisting apparatus other than the boom. In Figure 5 I have shown the unit Zl' mounted on the cabinstead of on the boom. In this arrangement,'. the cable 38 insteadof being simply attached'to the base of the apparatus is guided over pulleys 48 on the base and connected to a bracket 49 on the boom.

I claim: I

1. An automatic power cut-off appliance for a hoisting apparatus having a boom and power operated meansfor elevating same including a power disengaging member comprising a support carried by and movable withsaid boom, a flexible connection operatively interposed between said member andsupport and having a resilient portion therein, said connection operating to hold said member in power disengaging relation, a latch on said support for releasably holding said connection in inoperative position relative to said member, and a device for tripping saidlatch when said boom is in predetermined elevated position, comprising a connective member secured to a relatively stationary part of said apparatus and operatively to said'latch.

2. An automatic power cut-off appliance for a hoisting apparatus having a, boom and power 1 operated means for elevating same including a apparatus, a flexible connection means operatively connected between said member and said boom and having a yielding-extensible portion therein, said connection means operating to hold said member in powerdisengaging relation, a latch on said suppo'rtior releasably holding said connection means in inoperative position relative to said member, and a device for tripping said latch when said boom is in predetermined elevatedrelation, comprising a connective member operatively secured to said latch and to said boom; 1 v I 3. automatic power cut-oft appliance for a hoistingapparatus having a boom and power operated means for elevating same including a power disengaging member, comprising a casing arranged to be 'aflixed'to thetappa atus, an extensible spring anchored at one end therein, a slide reciprocatively mounted in said casing and secured to at another end to saidslide, a cable connectedto [said slide andoperatively to said member; said spring. and cable arranged and position ed to hold said member in power disengaged relation when thesp'ring is relatively contracted and the boomis in other thana predetermined elevated positiqn; a latch carried by said. casing and including a dog arranged therein and engageable with .saidislide to retain said spring in an extendedposition, and means having a part operatively connected with the boom for tripping said latch-to release said slide when the boom reaches said predetermined position;

JAMES E. "mvmrroar. 

